Sex differences in growth and carapace traits in the juvenile-crab instars in the mud crab <i>Scylla paramamosain</i> Estampador, 1950 (Decapoda: Brachyura: Portunidae)

Abstract We analyzed the differences in growth between female and male juvenile mud crabs (Scylla paramamosain Estampador, 1950) under standard individual rearing conditions using genetic sex makers we developed. The normality tests of the carapace length (CL) and width (CW) at each stages indicated that both CL and CW of mix sexes followed normal distribution model from the C1 to C3 stages, but not from the C4 and the subsequent stages, while these traits followed normal distribution model at the sex separated populations. No significant differences were observed in the CL, CW. and molting intervals between females and males from C1 to C3. The molting interval from C3 to C4 was shorter in females than in males, and the CW from C4 stages was significantly larger in females than in males, but the CL from C5 stages was significantly larger in males than in females. These observations might last into the adult stages, since the CW in similar rank adults was significantly larger in females than in males, and CL was the opposite. These studies provided for the first time direct evidence for the differentiation of growth between the sexes in mud crabs, providing insights for the breeding and aquaculture of this economically important species.